White’s prospects of winning are the best with a rook’s pawn since then the bishop has the least manoeuvring space. When the pawn is on the seventh, the black bishop does not have the short diagonal at all. White always wins provided he can prevent the enemy king from entering into the drawing zone defined by the rectangle a6-d6-d8. However, the win is by no means simple since there lurks a position with mutual zugzwang which must be handled the right way. The correct procedure was discovered by B. Horwitz in 1885!